The present invention concerns an automatic transmission for automobiles, and, more particularly, concerns an automatic transmission suitable for automobiles of the front engine front wheel drive or the rear engine rear wheel drive type, and relates to an improvement in the construction of such an automatic transmission, from the point of view of improvement of production efficiency.
As an automatic transmission for front engine front wheel drive or rear engine rear wheel drive automobiles, here is a known automatic transmission comprising a fluid torque converter which has a power input shaft at its one end and a power output shaft at its other end, a gear transmission mechanism comprising coaxially arranged input and output shafts and a plurality of hydraulic fluid pressure operated servo devices, which can be shifted between various speed stages by selective supply of control hydraulic fluid pressure to the hydraulic fluid operated control servo devices a hydraulic fluid pressure control device which controls said selective supply of control hydraulic fluid pressure to said hydraulic fluid pressure operated servo devices, a differential gear mechanism, and an endless chain power transmission mechanism, wherein the power output shaft of the fluid torque coverter is drivingly connected to the power input shaft of the gear transmission mechanism by the endless chain power transmission mechanism, and the power output shaft of the gear transmission mechanism is coaxially connected in a power transmitting fashion to the power input shaft of the differential gear mechanism.
For providing supply of hydraulic fluid pressure to the hydraulic fluid pressure control device mentioned above incorporated in such an automatic transmission, a hydraulic fluid pressure supply pump is required. Based upon the consideration that such a hydraulic fluid pressure supply pump should be directly driven from the power output shaft of the internal combustion engine of the automobile, without interposition of the fluid torque converter therebetween, it has generally been practiced for such a hydraulic fluid pressure supply pump to be driven by a hollow shaft which is directly connected to the input shaft of said fluid torque converter, said hollow shaft extending coaxially with respect to the output shaft of said fluid torque converter. In accordance with this, such a hydraulic fluid pressure supply pump has been mounted within a transaxle casing which has contained the fluid torque converter and the differential gear mechanism.
However, since the aforementioned hydraulic fluid pressure control device for providing control hydraulic fluid pressure to the various servo devices has been mounted within a transmission casing which has contained the gear transmission mechanism, during the assembly of such an automatic transmission for front engine front wheel drive or rear engine rear wheel drive type automobiles it becomes necessary to connect hydraulic fluid pipes between the aforesaid hydraulic fluid pressure supply pump, which is mounted in the transaxle casing, and the aforesaid hydraulic fluid pressure control device, which is mounted in the transmission casing, and this makes the work of assembling the automatic transmission more difficult, more complicated, and more expensive; and also another problem arises, in that if, after connecting such hydraulic fluid pipes, a defective seal occurs at one or the other of the connections thereof, this cannot be easily detected or repaired, because the transmission casing has already been coupled to the transaxle casing.
Another difficulty that has arisen relates to connecting hydraulic fluid conduits between the transmission casing and the transaxle casing, in order to conduct supply of hydraulic fluid pressure to, and conduct a governor hydraulic fluid pressure signal from, a governor hydraulic fluid pressure valve mounted rotatably to this transaxle housing. A simple way is required for connecting up such conduits reliably and effectively.
Yet another problem has arisen with regard to the provision of a hydraulic fluid suction or scavenge pipe, which sucks up hydraulic fluid from the bottom of the transmission casing, so as to recycle it through the hydraulic fluid pressure supply pump. Such a pipe, by its nature, has to be rather long. If it is formed in one piece, as has been the case in the prior art, difficulty may well arise in fitting this pipe to the transmission casing, and misalignment of this pipe, either in the axial direction, or angularly, can cause air leakage at the places where it should form a tight seal with the transmission casing, thus endangering the whole functioning of the transmission.